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AUSTRALASIAN ANTS OF THE GENUS LEPTOTHORAX MAYR (HYMENOPTERA : 

FORMICIDAE : MYRMICINAE) 

Robert W. Taylor 



Taylor, R.W. 1989 11 13: Australasian ants of the genus Leptothorax Mayr (Hymenoptera : 
Formicidae : Myrmicinae). Mem. QdMus. 27(2): 605-610. Brisbane. ISSN 0079-8835. 

The following species are discussed: L. bilongrudi sp. nov. (Papua New Guinea), L. australis 
Wheeler, and L. renateae sp. nov. (both North Queensland). The Australian species have 
peculiar lateral subocular carinae. Leptothorax, as presently constituted, is otherwise unknown 
from the Indo-Australian area. 
OAnts, Formicidae, taxonomy, Leptothorax, Myrmicinae. 

Robert W. Taylor, Australian National Insect Collection, CSIRO Division of Entomology, 
GPO Box 1700, Canberra, Australian Capital Territory 2601, Australia; 30 November, 1988. 



Leptothorax is a large and important myrmicine 
ant genus with over 200 nominal species known 
from the Palearctic, Ethiopian, Nearctic and Neo- 
tropical regions. Its diagnosis, synonymy and dis- 
tribution were reviewed, with a monograph of the 
11 Afrotropical species, by Bolton (1982). Apart 
from the three species considered here the genus 
has not been reported from the Indo-Australian 
area south of the Tropic of Cancer and east of 
Bangladesh (if one excludes the possibility, now 
under investigation by the author, that the Aus- 
tralian regional generic names Podomyrma Fr. 
Smith, Dacryon Forel, and Pseudopodomyrma 
Crawley, which were synonymised under 
Podomyrma by Taylor and D.R. Brown (1985), 
should all properly be considered junior synonyms 
of Leptothorax). The Sumatran generic record 
mentioned in passing by Wheeler (1934), when he 
described L. australis from north Queensland, 
seems never to have been substantiated. L. bilon- 
grudi sp. nov. is the first species to be described 
from New Guinea, and L. renateae sp. nov. the 
second from Australia. These ants are poorly rep- 
resented in collections, perhaps because they nest 
and forage arboreally and would thus tend to be 
overlooked by most ant collectors. In any case they 
appear to be rare. The three are apparently closely 
related; all have a typical Leptothorax palpal 
formula (maxillary 5:labial 3; confirmed in each 
by dissection), with 12-segmented antennae, 
unusual mandibular dentition, (described below 
under L. bilongrudi), and angularly projecting 
dorsolateral mesonotal borders. Twelve- 
segmented antennae are more usual than the alter- 
native 1 1 in Leptothorax, and mesonotal projec- 
tions are found in some neotropical species 
(Kempf, 1958, 1959). The mandibular dentition, 
however, apparently sets these species apart from 
all other members of the genus. In addition, the 
Australian species both have an unusual subocular 



carinal complex on either side of the head. Each 
of these consists of a pair of equally very fine, 
closely parallel carinae, separated by a minute 
groove, which is about equal in width to an indi- 
vidual carina. These run together from the man- 
dibular bases to meet the occipital carina on each 
side at an obhque angle (Fig. 4). Such structures 
have not been reported from other Leptothorax 
species. Somewhat similar carinae are seen in some 
species of Myrmecina Curtis, but otherwise they 
appear uniquely to characterise L. australis and L. 
renateae. Some records are cited using 1 degree 
coordinates to indicate mapping grid cells, as in 
Taylor (1987). 

Specimens studied here are from the Australian 
National Insect Collection (ANIC) and the 
Queensland Museum (QM). Abbreviations for 
other collections are: BISHOP — B.P. Bishop 
Museum, Honolulu, Hawaii, USA; BM(NH) — 
British Museum (Natural History), London; GM 
— Museum d'Histoire Naturelle, Geneva, Switz- 
erland; KUB — Masao Kubota collection, 
Odawara City, Japan; MCZ — Museum of Com- 
parative Zoology, Cambridge, Massachusetts, 
USA. Conventions for measurements and indices 
follow Bolton (1982); HL is maximum head 
length, and HW the maximum width of the head 
behind the eyes. 

Leptothorax bilongrudi sp. nov. 
(Figs 1-3) 

Type Locality 

Papua New Guinea: West Sepik Province, Victor 
Emanuel Range, at 5°07'S, 141°38'E, near Telefomin. 



Material Examined and Distribution 

Known only from the type locality: holotype worker, 
1 1 paratype workers, 2 paratype dealate females, taken 
at 1550 m (R.J. Kohout acc.1984.305, 17-19 Aug.). 



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MEMOIRS OF THE QUEENSLAND MUSEUM 



Holotype gold-coated for scanning electron microscopy, 
mounted with a colour-matched paratype. Holotype, 
most paratypes, including females, in ANIC (type No. 
7774), worker paratypes in BISHOP, BM(NH), GM, 
KUB, MCZ, QM. 

Etymology 

Named for the collector, Rudolf Kohout. The 
specific epithet is undeclinable Papua New Guinea 
pidgin, meaning 'belonging to Rudl'. 



Worker 

Dimensions (mm, holotype, smallest paratype, 
largest paratype (ranked by HW)): TL c. 4.5-6.2; 
HL 1.14, 0.98, 1.24; HW 0.96, 0.84, 1.24; CI 84, 
86, 89; SL 1.16, 0.97, 1.27; SI 102, 99, 102; PW 
0.75, 0.63, 0.83; AL 1.56, 1.34, 1.77. General 
features as in Figs 1-3. Mandibular dentition 
unusual for Leptothorax; consisting of 3 apical 
and 2 basal teeth separated by a long, minutely 




Figs 1-3. Leptothorax bilongrudi, holotype worker, standard views. HW 0.96 mm; PW 0.75 mm; AL 1.56 mm. 



AUSTRALASIAN LEPTOTHORAX 



607 



crenulate, edentate blade; third apical tooth 
separated from second by a brief diastema; basal 
tooth formed from the slightly raised obtuse angle 
separating the inner and posterior mandibular 
borders. Median anterior clypeal border minutely 
emarginate; median clypeal carina barely differ- 
entiated from surrounding sculptural elements; 
frontal area a shallow depression. Eyes almost 
hemispherical, their longest diameters spanning 
12-15 facets. Frontal carinae and lateral suborbi- 
tal carinae lacking. Occipital border evenly arched 
in frontal view. A distinct occipital carina closely 
encloses the nape, and extends anteromedially on 
each side below the head to terminate on the 
postgena at about the level of the posterior border 
of the adjacent eye, short of the genal suture. 
Antennae 12-segmented, club 3- segmented, dif- 
ferentiated by the relative length of its segments, 
rather than by a marked step in their thickness; 
scapes when extended exceeding occipital border 
by around 1/3 their length. In dorsal view, 
pronotal collar relatively broad; humeri evenly 
rounded. Mesonotum narrow, separated from 
pronotum by a shallow, depressed sutural 
remnant; dorsolateral borders extended as acute 
salient projections terminating a slightly raised 
obtuse transverse crest. Propodeal spines long, 
posterodorsolaterally divergent, almost straight, 
with apices minutely upturned. Metapleural lobes 
somewhat salient, narrowly rounded. Petiolar 
peduncle proportionatly very long and distinctly 
set-off from the node; spiracular rims slightly 
raised in dorsal view; subpetiolar process a minute 
anteroventral angle; node rounded in all direc- 
tions, almost hemispherical, slightly longer than 
wide in dorsal view. Postpetiole as illustrated, 
almost circular in dorsal view, minutely wider than 
long. Sting somewhat transversely flattened and 
blade-like. 

Mandibles smooth, except for piligerous 
punctures and faint, effaced traces of longitudinal 
sculpturing on their bases and outer borders. 
Clypeus with spaced longitudinal rugae. Frons 
rugoreticulate, more so posteriorly; interstitial 
microsculpture obscure, except on each side 
between the antennal insertion and eye; sculptural 
intensity diminishing progressively below the eyes; 
postgenae essentially smooth. Mesosoma less 
intensively sculptured than head; sculpture of 
petiole and postpetiole even more reduced; gaster 
smooth and shining, with a few very short basal 
ribs surrounding its juticular condyle. Pilosity as 
illustrated; the hairs tapered and apically pointed; 
those on gastral dorsum scattered, separated by 
almost their average length. Colour medium-dark 



brown with a reddish-orange cast under magnifi- 
cation, scapes and legs a little lighter, antennal 
funiculi medium-brown. 

Female 

The largest female paratype has HW 1.17, and 
the smallest: HL 1.27; HW 1.10; CI 87; SL 1.15; 
SI 105; scutum W 0.92; AL 1.90. Differing from 
the worker in the usual features. Ocelli small, sur- 
rounding a slightly raised triangle into which each 
is somewhat inserted and directed more-or-less 
outwards. Scapes relatively short, exceeding 
occipital border by about 1/4 their length when 
extended. Scutum lacking notaulices or parapsidal 
lines. Anterolateral corners of scutellum extended 
laterally as rounded, minutely bowl-shaped lobes 
(possible homologues of the worker mesonotal 
extensions). Petiolar peduncle shorter and more 
tapered than in worker. Postpetiole distinctly 
broader than long in dorsal view. Propodeal spines 
relatively short, less divergent than in worker; 
about as long as the petiolar peduncle, as also in 
the worker. 

Sculpturing much as in worker; the frons more 
closely reticulate, with more distinct interstitial 
mcirosculpture; postgenae with quite strong, 
somewhat effaced sculpture. Mesosomal sculptur- 
ing relatively strong, more as on the frons. Pilosity 
and colour as in worker. 



Leptothorax australis Wheeler 

Leptothorax australis Wheeler, 1934: 60, worker. Type 
locality: Queensland, Cairns District. (L. (Goni- 
othorax) australis). Holotype in MCZ (examined). 



Material Examined and Distribution 

Known only from north Queensland (grid cells 16/145 
and 17/145; provisionally also 11/142 (female record)). 
Modern records are: Bellenden Ker Range, cableway base 
station, worker, 100 m (Earthwatch/Queensland 
Museum, 25-31 Oct. 1981, QM); Palmerston N.P., 9 
workers on branch of recently felled giant rainforest tree 
(B.B. Lowery, 5.8.1975, ANIC, BM(NH), GM, MCZ); 
8 km W of TuUy, near Rocky Ck Bridge, 3 workers, in 
dead vine, lowland rainforest (B.B. Lowery, 22.9.1980, 
ANIC, QM). An alate female provisionally identified as 
L. australis (see below) was collected much further north: 
15 km W of Capt. Billy Creek, Great Dividing Range 
(11°40'S, 142°45'E), (G.B. Monteith, 4-9.vii.1975). 

Worker 

The smallest and largest available specimens 
(both from Palmerston N.P.) have the following 
dimensions (mm): TL c. 2.3, 2.6; HL 0.74, 0.78; 



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MEMOIRS OF THE QUEENSLAND MUSEUM 



HW 0.63, 0.68; CI 85, 87; SL 0.49, 0.53; SI 78, 
78; PW 0.46, 0.50; AL 0.90, 1.00. General features 
as in the original description, which omitted 
reference to the suborbital carinae (which are 
obscured on the holotype by mounting glue). They 
are almost exactly as illustrated for L. renateae 
(Fig. 4), except that each is more nearly straight 
below the eye. The sculpturing below the carinae 
is more finely textured and less reticulate than that 
above, unlike L. renateae, where both areas are 
similarly configured. The suborbital carinae are 
not homologous with the postgenal extensions of 
the occipital carina described for L. bilongrudi, 
since the latter are also present in L. australis. 



Mandibular dentition as described above for L. 
bilongrudi; the third apical tooth disporportion- 
atly sm£ill; the two posterior teeth vestigal. 
Female 

The female listed above is only slightly larger 
than the workers (HL 0.75, AL 1.21), and agrees 
with their salient features, including details of hair 
structure, propodeal spine length, and configura- 
tion of the sculpturing above and below the subor- 
bital carinae. The petiolar node is slightly .longer 
than wide in dorsal view, proportioned much as in 
L. renateae workers, but with the anterodorsal 
border less convex. There are no traces of frontal 
carinae. 




Figs 4-7. Leptothorax renateae, holotype worker: 4, lateral view of head, showing suborbital carina; 5-7, standard 
views. HW 0.71 mm; PW 0.49; AL 1.10 mm. 



AUSTRALASIAN LEPTOTHORAX 



609 



Leptothorax renateae sp. nov. 
(Figs 4-7) 



Type Locality 

Queensland: U km ENE of Mt Tozer (12°43'S, 
143°18'E). 

Material Examined and Distribution 

Known only from north Queensland (grid cells 12/ 
143, 16/145): Mt Tozer area (distances and bearings from 
Mt Tozer): type locality, holotype worker, paratype 
worker (T. Weir, 11-16 July 1986, rainforest litter, ANIC 
berlesate 1064); same data but 3 km ENE, 12°44'S, 
HS^M'E, paratype worker (1-4 July 1986, ANIC 
berlesate 1052). Iron Range, E Claudie River, 20 m, 
dealate female (G. Monteith, 6 Dec. 1985, rainforest, 
stick brushing, QM berlesate 694). Cape Tribulation area 
(distances and bearings from the Cape, all coll. Monteith, 
Yeates and Thompson, 1982, rainforest pyrethrum 
knockdown samples): 2.0 km WNW (site 2), 7 Oct., 50 
m, 2 paratype workers; 3.5 km W (site 7), 2 Oct., 680 
m, dealate female; 4.5 km W (site 9), 2 Sep., 760 m, 
dealate female. Cape Tribulation area, 16°03' to 
16°05'S, 145°28'E, littoral rainforest, paratype worker 
(A. Calder and T. Weir, 21-28 Mar. 1984, ANIC 
berlesate 940). Mossman Gorge, 3 mi E of Mossman, 
rainforest, paratype worker, c. 200 ft (R.W. Taylor 
ace. 1966.90, 27-29 X.). All worker specimens except 
holotype designated paratypes; the females are only pro- 
visionally identified, and are not designated as paratypes. 
Holotype, most paratypes, and females, in ANIC (type 
No. 7773), worker paratypes in BM(NH), QM. Holotype 
gold-coated for scanning electron microscopy, mounted 
with a colour-matched paratype. 

Etymology 

Named with gratitude for my assistant Renate 
Sadler. 

Worker 

Dimensions (mm) of the smallest paratype 
(Cape Tribulation) and the holotype (the largest 
type) are: TL c. 3.4, 3.6; HL 0.74, 0.77; HW 0.63, 
0.71 ; CI 86, 92; SL 0.57, 0.57; SI 90, 80; PW 0.49, 
0.52; AL 0.97, 1.10. General features as in Figs 4- 
7. Very similar to L. australis, and agreeing in 
general with its original description, with the 
following differences: (1) Faint vestiges of frontal 
carinae present on head, extending back from 
posterior extremities of frontal lobes to slightly 
beyond level of posterior margins of eyes; each 
carina is essentially a minutely raised element of 
the longitudinal sculpturing, and is usually better 
developed posteriorly than in its medial section. 
There are no traces of such structures in L. 
australis, and they are more distinct in southern 
than northern specimens of L. renateae. (2) 
Pronotal humeri evenly rounded in dorsal view, 



versus epaulate in L. australis. (3) Propodeal 
spines 1.3-1.5 times longer than the distance sep- 
arating their bases, versus about as long as that 
distance in L. australis. (4) Petiolar node in dorsal 
view distinctly longer than wide, versus sUghtly 
wider than long in L. australis. (5) Lateral 
mesonotal projections larger and more prominent. 
(6) Pilosity consisting of moderately long tapered 
hairs with narrowly acute apices, relatively about 
1.5-2 times as long as those of L. australis, which 
has untapered, blunt, minutely clubbed hairs. 
Mandibular dentition and suborbital carinae much 
as in L. australis. Southern specimens tend to be 
smaller, with proportionately narrow heads and 
long scapes. 

Female 

The females listed above are only slightly larger 
than the workers, and agree with them in the same 
features noted above for L. australis. Frontal 
carinae as in worker; petiolar node in dorsal view 
relatively slightly longer proportional to its width. 
The mesosoma relatively bulky in the Iron Range 
specimen. 



KEY TO AUSTRALASIAN LEPTOTHORAX 
SPECIES (WORKERS AND FEMALES) 

1 . Subocular carinae present on each side of head, 
extending from mandibular base to occipital 
carina (Fig. 4); scapes short, failing to reach 
occipital border when laid back (Fig. 5); Aus- 
tralian species 2 

Subocular carinae lacking (Fig. 3); scapes rel- 
atively long, clearly exceeding occipital border 
when laid back (Fig. 1); New Guinean 
species L. bilongrudi sp. nov. 

2. Pilosity consisting of moderately long, tapered 
hairs with finely acute apices (Fig. 7); petiolar 
node distinctly longer than broad in dorsal view 

L. renateae sp. nov. 

Pilosity consisting of short, blunt or minutely 
clubbed hairs, proportionately about 1/2 to 
2/3 as long as those in Fig. 7; petiolar node in 
dorsal view as broad or slightly broader than 
long L. australis WheeleT 

ACKNOWLEDGEMENTS 

The cooperation of Rev. B.B. Lowery SJ, 
Rudolf Kohout, Dr G.B. Monteith and Barry 
Bolton is gratefully acknowledged. Colin Beaton 
assisted with the preparation of the figures. 



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MEMOIRS OF THE QUEENSLAND MUSEUM 



LITERATURE CITED 

Bolton, B. 1982. Afrotropical species of the myrmicine 
ant genera Cardiocondyla, Leptothorax, Melissotar- 
sus, Messor and Cataulacus. Bull. Br. Mus. nat. Hist. 
(Entomology) 45(4): 307-370. 

Kempf, W.W. 1958. Sobre algumas formigas neotrdpi- 
cas do gSnero Leptothorax Mayr. An. Acad. Brasi- 
leira de Ci^ncias 30: 91-102. 

1959. A synopsis of the New World species belonging 
to the Nesomyrmex-gioup of the ant genus Lepto- 
thorax Mayi. Studiaent. 2: 391-432. 



Taylor, R.W. 1987. A checklist of the ants of Australia, 

New Caledonia and New Zealand. CSIRO Aust. Div. 

Ent. Rep. 41: 1-92. 
Taylor, R.W. and Brown, D.R. 1985. Hymenoptera: 

Formicidae. In 'Zoological Catalogue of Australia. 

Volume 2'. p. 1-149, 306-348. (Austrahan Govt 

Printing Service: Canberra). 381 pp. 
Wheeler, W.M. 1934. An Australian ant of the genus 

Leptothorax Mayr. Psyche Camb. 31: 60-62.